Influence of Post-Application Irrigation on Control of Annual White Grubs on a Golf Course Fair-Way, 1996

This study was conducted in Lincoln, NE on a golf course fairway. The turf (20% Kentucky bluegrass and 80% perennial rye) was maintained at a mowing height of 11/16 inch. Thatch accumulation (finger compressed) in the plot area was 0.375 to 0.50 inch. Field conditions at the study site were: soil type, silty clay loam; soil organic matter, 4%; soil pH, 6.2; water pH, 7.0. Environmental conditions at the time of application were as follows: soil moisture 12% by wt.; air temperature 72°F; soil temperature 72°F; relative humidity 43%; wind direction and velocity 6° at 7 mph. Plots were 6 X 10 ft and the experimental design was a RCB with 3 replications. Insecticides were applied once on 9 Jul and twice on 11 Jul. Liquids were applied using a CO2 sprayer with a TeeJet® 8002 nozzle at 30 psi and delivering 2 gal/1000 square feet. A pre-calibrated Gandy 24H12 drop spreader was used to apply granular insecticides. Post-application irrigations were applied as follows: 09 Jul application, none; 11 Jul, first application, 0.35 inch; 11 Jul, second application with syringe, approximately 0.125 inch. Normal irrigation was resumed after 48 h. Precipitation between application and evaluation totaled 11.3 inches. Treatments were evaluated 57 DAT on 4 SEP by removing from each plot three, 8-inch diam turf-soil cores (1.05 ft2 total area) to a depth of 3 inches and counting the number of surviving grubs. Insecticides were applied prior to the onset of masked chafer oviposition.